CN113359030A - Wind driven generator short circuit fault simulation platform based on external magnetic flux leakage detection - Google Patents
Wind driven generator short circuit fault simulation platform based on external magnetic flux leakage detection Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention belongs to the technical field of fault diagnosis of wind driven generators and discloses a wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection, which is used for simulating the actual operation condition of a generator and different short-circuit fault types of the generator and comprises a double-fed wind driven generator, a dragging motor, a frequency converter, a double-fed converter, a short-circuit switch cabinet, a short-circuit switch console and a magnetic flux leakage monitoring module, wherein the short-circuit switch console is respectively connected with the short-circuit switch cabinet and the frequency converter, the short-circuit switch cabinet is connected with the double-fed wind driven generator, the frequency converter is connected with the double-fed wind driven generator through the dragging motor, and the double-fed wind driven generator is also respectively connected with the double-fed converter and the magnetic flux leakage monitoring module. The invention provides a simulation platform suitable for simulating the short-circuit fault of a double-fed wind driven generator, and enriches the practical engineering application.
Description
Technical Field
The invention belongs to the technical field of fault diagnosis of wind driven generators, and particularly relates to a wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection.
Background
With the rapid development of the wind power industry, the doubly-fed wind generator is widely applied due to a plurality of advantages. The working environment of the doubly-fed wind generator is complex and severe, faults are easy to occur, normal operation of the wind turbine generator is directly influenced, and a grid-connected system is endangered. According to survey data, the short-circuit fault of the stator and the rotor of the wind driven generator is one of main reasons for damage and shutdown of the wind turbine generator, the short-circuit fault of the stator and the rotor is mostly caused by turn-to-turn short circuit of a coil, once the short circuit occurs, the rotor is electrified, shaft current is generated, the motor is seriously damaged, the unit is difficult to maintain, and the maintenance cost is high.
At present, measurement of current, vibration and rotating speed is mostly focused on in the aspect of short-circuit fault diagnosis application of a generator, motor current characteristic analysis is most widely applied, wrong motor current indexes are reported to be possibly caused by magnetic asymmetry of a rotor structure, a rotor magnetic field detection is carried out by using a detection coil method, the magnetic symmetry condition can be observed, however, the detection coil is mostly arranged on the surface of an air gap of a stator core, and the invasive monitoring method is difficult to install for a set which is already put into operation and is inconvenient for practical application of engineering.
The fault monitoring of the induction motor based on external magnetic flux measurement is widely concerned by wind power enterprises in recent years due to the advantages of low potential cost and simple and convenient installation. Although the diagnosis based on the monitoring of the external magnetic flux leakage of the generator can provide the characteristic which is comparable to the characteristic analysis of the current of the generator, the characteristic frequency components of the magnetic flux leakage signal can be covered to a certain extent due to the characteristic that the weak external magnetic flux leakage signal has random broadband of environmental noise in a strong noise environment, particularly when the environmental noise is strong, the external interference is very easy to be received, the relatively weak characteristic frequency is completely submerged in the noise, and the current research mostly takes a single or double sensor detection channel as the main, the performance and reliability of the fault detection method are influenced, the false fault magnetic flux leakage alarm is very easy to be caused, the practical application of the fault detection method is limited, the current research still takes the experimental research as the main, meanwhile, the structure of the generator adopted in the experimental research is greatly different from the actual structure of the doubly-fed generator, and the number of fault types which can be simulated on the same test platform is small, it is necessary to conduct further research on a wind turbine short-circuit fault simulation and diagnosis method based on external magnetic flux leakage detection.
The method for diagnosing the wind driven generator is simple, effective and low in cost, effectively extracts the short-circuit fault information of the generator, and becomes one of the technical problems to be solved urgently in the field.
Disclosure of Invention
The invention aims to provide a wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection, which is used for solving the problem that a proper experiment table is lacked for wind driven generator short-circuit fault simulation and diagnosis in the prior art.
In order to realize the task, the invention adopts the following technical scheme:
the wind driven generator short-circuit fault simulation platform is used for simulating the actual operation condition of a double-fed wind driven generator and different short-circuit fault types of the double-fed wind driven generator and comprises the double-fed wind driven generator, a dragging motor, a frequency converter, a double-fed converter, a short-circuit switch cabinet, a short-circuit switch console and a magnetic leakage flux monitoring module, wherein the short-circuit switch console is respectively connected with the short-circuit switch cabinet and the frequency converter, the short-circuit switch cabinet is connected with the double-fed wind driven generator, the dragging motor drives the double-fed wind driven generator through the frequency converter, and the double-fed wind driven generator is also respectively connected with the double-fed converter and the magnetic leakage flux monitoring module;
the dragging motor is used for driving the double-fed wind driven generator; the frequency converter is used for adjusting the frequency and the rotating speed of the dragging motor; the double-fed converter is used for adjusting the output power and the load of the double-fed wind driven generator; the double-fed wind driven generator is characterized in that a plurality of winding taps are led out from each phase of stator and rotor winding coils of the double-fed wind driven generator, winding tap leads are connected to a junction box wiring terminal block of the generator, the number of the winding leads, the junction box wiring terminal block and the type of short-circuit faults are in one-to-one correspondence, the winding taps are connected with an external short-circuit switch cabinet through the junction box wiring terminal block, and the short-circuit faults with different turns are realized through the mutual connection of the winding taps; the short-circuit switch cabinet is used for simulating the short-circuit fault of the double-fed wind driven generator and is connected with a tap lead of a winding of the double-fed wind driven generator through a short-circuit control circuit to simulate and control external short circuit; the short-circuit switch console is used for controlling a short-circuit control circuit in the short-circuit switch cabinet; the leakage magnetic flux monitoring module is used for acquiring an external leakage magnetic signal of the doubly-fed wind generator and carrying out signal analysis and visual display on the external leakage magnetic signal;
the short-circuit switch cabinet comprises a short-circuit control circuit and a short-circuit protection resistor, wherein an alternating current contactor and a circuit breaker are connected in series in the short-circuit control circuit, the alternating current contactor is in a normally open state, and the short-circuit protection resistor is connected into the short-circuit control circuit and used for limiting current and protecting the double-fed wind driven generator from repeatedly carrying out short-circuit experiments for multiple times. The short circuit control circuit is connected with the junction box of the double-fed wind driven generator, and the short circuit switch control console controls the auxiliary contact of the alternating current contactor to be attracted, so that turn-to-turn short circuit faults are caused. The magnetic leakage flux monitoring module comprises a magnetic ring antenna array, a digital acquisition card and a portable computer, wherein the magnetic ring antenna array comprises a plurality of magnetic ring antennas, the output ends of the magnetic ring antennas are connected with the digital acquisition card, the magnetic ring antennas are arranged at different axial and radial positions of the doubly-fed wind driven generator, the digital acquisition card is used for acquiring magnetic leakage signals monitored by the magnetic ring antennas at different positions, and the portable computer performs data analysis and visual display on the acquired magnetic leakage signals through a C # virtual instrument.
Furthermore, the short-circuit control circuit is sequentially connected with a junction box wiring terminal block row of the doubly-fed wind driven generator, a circuit breaker, an alternating current contactor and a short-circuit protection resistor, wherein the junction box wiring terminal block row of the doubly-fed wind driven generator is arranged on tap leads of different numbers of a stator winding and a rotor winding of the doubly-fed wind driven generator;
furthermore, the leading-out positions of the tap lead wires comprise stator windings of the doubly-fed wind generator, different-phase slots of rotor windings, same coils of different branches of the same phase and coil ends.
Furthermore, the short-circuit switch console adopts a PLC (programmable logic controller) to control the switching action of the short-circuit switch cabinet, controls the auxiliary contact of the AC contactor to be electrified and be attracted to cause turn-to-turn short-circuit fault, and controls the auxiliary contact of the AC contactor to be attracted for 1s and then be disconnected after power failure, so that the doubly-fed wind driven generator can recover to normally operate.
Further, the portable computer performs signal data analysis and visual display on the acquired magnetic leakage signal through a C # virtual instrument, and the method comprises the following steps:
step 1: acquiring magnetic flux leakage signals monitored by magnetic ring antennas at different positions of the doubly-fed wind generator through a digital acquisition card;
step 2: performing time domain analysis after wavelet denoising on the acquired leakage magnetic flux signal to judge the fluctuation condition of the leakage magnetic flux signal, and further extracting leakage magnetic flux signal data in a stationary time period according to fluctuation positioning information of the leakage magnetic flux signal;
and step 3: carrying out envelope analysis on the leakage flux signal in the stable time period to extract an envelope signal, carrying out double-spectrum analysis after carrying out Hilbert transform on the envelope signal, and obtaining a double-spectrum estimation characteristic diagram of the leakage flux signal;
and 4, step 4: and carrying out 1.5-dimensional slicing processing on the bispectrum estimation characteristic diagram of the magnetic leakage signal to obtain a 1.5-dimensional envelope spectrogram, carrying out visual display on the obtained 1.5-dimensional envelope spectrogram, further obtaining the characteristic coupling frequency of the magnetic leakage signal, and judging whether the winding short-circuit fault exists or not through comparison and analysis with the spectrogram of the magnetic leakage signal of the normal operation of the doubly-fed wind driven generator.
Furthermore, the plane of the magnetic loop antenna is parallel to the end part of the doubly-fed wind driven generator and the radial housing, and the number of the magnetic loop antennas is at least two and the magnetic loop antennas are arranged at the end part of the doubly-fed wind driven generator and in the radial direction of the housing.
Furthermore, the number of the magnetic loop antennas is one in the axial position of the driving end of the doubly-fed wind driven generator, one in the axial position of the non-driving end of the doubly-fed wind driven generator, and three in the radial direction of the machine shell.
Compared with the prior art, the invention has the following technical characteristics:
(1) the invention designs and builds a 100kW double-fed wind driven generator winding short-circuit fault simulation experiment platform, which comprises a variable frequency motor, a double-fed wind driven generator, a double-fed current transformer, a short-circuit control switch cabinet, a short-circuit control console and a magnetic leakage flux monitoring module consisting of a magnetic ring antenna array, a digital acquisition card and a portable computer PC. Compared with the low-power grade commonly adopted at home and abroad at present, the 100kW high-power double-fed induction motor short-circuit fault experimental simulation platform designed and developed can better simulate the performance of a generator running in an actual wind field, short circuits between different taps are led out through each phase winding of the generator in a junction box, stators of different types and rotor winding short-circuit faults are simulated, meanwhile, magnetic leakage flux monitoring modules acquire external magnetic leakage flux signals of the generator through magnetic ring antenna arrays, an important tool is provided for development of short-circuit fault simulation experimental research, experimental results are more practically laminated, and the high-power double-fed induction motor short-circuit fault experimental simulation platform has higher reference value.
(2) According to the double-fed wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection, magnetic flux leakage signals at different axial and radial positions outside a double-fed induction generator during different types of short-circuit faults of the double-fed induction generator are subjected to experimental research and analysis through the magnetic loop antenna magnetic flux leakage array, the change characteristics of the magnetic flux leakage at different positions outside the double-fed induction generator during short circuit with different turns are obtained, the optimal arrangement mode of the magnetic flux leakage array is determined, a processing method suitable for magnetic flux leakage signal analysis is adopted, the magnetic flux leakage signal fault characteristics under a strong noise environment can be effectively extracted through 1.5-dimensional envelope spectrum analysis, the technical problem of external magnetic flux leakage measurement of the double-fed induction generator in practical application is solved, and engineering practice application is easy.
(3) According to the leakage flux monitoring module, the leakage flux monitoring array is constructed outside the doubly-fed wind driven generator through the magnetic ring antenna, the magnetic ring antenna sensors are placed at different axial and radial positions of the doubly-fed wind driven generator, fault diagnosis of short-circuit faults of a stator and a rotor of the generator is realized, the adopted method for carrying out short-circuit diagnosis on the leakage flux array of the generator is non-invasive, only the magnetic ring antenna array needs to be placed at the proper position of the motor, and the short-circuit fault simulation platform and the different types of short-circuit fault realization modes are convenient to apply and realize in engineering, and the short-circuit operation condition of the generator can be simulated really, so that the simulation realization of winding short-circuit faults and the research on the fault detection method have important engineering value.
Drawings
FIG. 1 is a schematic diagram of a short-circuit fault experimental platform of a doubly-fed wind generator;
FIG. 2 is a schematic view of the positions of the stator end lead-out wires;
FIG. 3 is a schematic diagram of a stator and a rotor connection mode and a short circuit of a doubly-fed wind generator;
FIG. 4 is a PLC programmable controller control circuit;
FIG. 5 is a schematic view of a magnetic loop antenna array testing position;
fig. 6(a) is a measured magnetic flux leakage signal at the end of the non-driving end when 8 turns of the stator winding are short-circuited;
fig. 6(b) is a measured magnetic flux leakage signal at the end of the driving end when 8 turns of the stator winding are short-circuited;
fig. 6(c) is a magnetic flux leakage actual measurement signal in the radial direction (measurement point 1) when the stator winding is short-circuited by 8 turns;
fig. 6(d) is a magnetic flux leakage actual measurement signal in the radial direction (measuring point 2) when the stator winding is short-circuited by 8 turns;
fig. 6(e) is a magnetic flux leakage actual measurement signal in the radial direction (measuring point 3) when the stator winding is short-circuited by 8 turns;
FIG. 7 is a frequency spectrum analysis of axial flux leakage when the rotor winding is short circuited with different turns;
FIG. 8 is a bispectrum analysis of non-drive end axial flux leakage when a rotor winding is shorted;
FIG. 8(a) is a bispectrum estimation feature diagram of axial flux leakage at a non-driving end during normal operation;
FIG. 8(b) is a bispectrum estimation feature diagram of non-drive end axial flux leakage when 8 turns of the rotor winding are short-circuited;
FIG. 9(a) is a 1.5-dimensional envelope spectrum of axial flux leakage in normal operation;
FIG. 9(b) is a 1.5-dimensional envelope spectrum of axial flux leakage when the rotor is short-circuited by 2 turns;
FIG. 9(c) is a 1.5-dimensional envelope spectrum of axial flux leakage when 5 turns of the rotor are short-circuited;
fig. 9(d) is a 1.5-dimensional envelope spectrum of axial flux leakage when the rotor is short-circuited by 8 turns.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The platform is used for simulating the actual operation condition of the doubly-fed wind generator and different short-circuit fault types of the doubly-fed wind generator and comprises the doubly-fed wind generator, a dragging motor, a frequency converter, a doubly-fed converter, a short-circuit switch cabinet, a short-circuit switch console and a magnetic leakage flux monitoring module, wherein the short-circuit switch console is respectively connected with the short-circuit switch cabinet and the frequency converter, the short-circuit switch cabinet is connected with the doubly-fed wind generator, the frequency converter is connected with the doubly-fed wind generator through the dragging motor, and the doubly-fed wind generator is respectively connected with the doubly-fed converter and the magnetic leakage flux monitoring module;
the dragging motor is used for driving the double-fed wind driven generator; the frequency converter is used for adjusting the frequency and the rotating speed of the dragging motor; the double-fed converter is used for adjusting the output power and the load of the double-fed wind driven generator; the double-fed wind driven generator is characterized in that a plurality of winding taps are led out from each phase of stator and rotor winding coils of the double-fed wind driven generator, winding tap leads are connected to a junction box wiring terminal block of the generator, the number of the winding leads, the junction box wiring terminal block and the type of short-circuit faults are in one-to-one correspondence, the winding taps are connected with an external short-circuit switch cabinet through the junction box wiring terminal block, and the short-circuit faults with different turns are realized through the mutual connection of the winding taps; the short-circuit switch cabinet is used for simulating the short-circuit fault of the double-fed wind driven generator and is connected with a tap lead of a winding of the double-fed wind driven generator through a short-circuit control circuit to simulate and control external short circuit; the short-circuit switch console is used for controlling a short-circuit control circuit in the short-circuit switch cabinet; the leakage magnetic flux monitoring module is used for acquiring an external leakage magnetic signal of the doubly-fed wind generator and carrying out signal analysis and visual display on the external leakage magnetic signal;
the short-circuit switch cabinet comprises a short-circuit control circuit and a short-circuit protection resistor, wherein an alternating current contactor and a circuit breaker are connected in series in the short-circuit control circuit, the alternating current contactor is in a normally open state, and the short-circuit protection resistor is connected into the short-circuit control circuit and used for limiting current and protecting the wind driven generator from repeatedly carrying out short-circuit experiments for multiple times. The short circuit control circuit is connected with the junction box of the double-fed wind driven generator, and the short circuit switch control console controls the auxiliary contact of the alternating current contactor to be attracted, so that turn-to-turn short circuit faults are caused. The magnetic leakage flux monitoring module comprises a magnetic ring antenna array, a digital acquisition card and a portable computer, wherein the magnetic ring antenna array comprises a plurality of magnetic ring antennas, the output ends of the magnetic ring antennas are connected with the digital acquisition card, the magnetic ring antennas are arranged at different axial and radial positions of the doubly-fed wind driven generator, the digital acquisition card is used for acquiring magnetic leakage signals monitored by the magnetic ring antennas at different positions, and the portable computer performs data analysis and visual display on the acquired magnetic leakage signals through a C # virtual instrument.
Specifically, the short-circuit control circuit is sequentially connected with a junction box terminal block row of the doubly-fed wind driven generator, a circuit breaker, an alternating current contactor and a short-circuit protection resistor, wherein the junction box terminal block row of the doubly-fed wind driven generator is arranged on tap leads of different numbers of a stator winding and a rotor winding of the generator; the short-circuit faults include stator, rotor turn-to-turn short-circuit faults, phase-to-phase short-circuit faults, interlayer short-circuit faults and ground short-circuit faults.
Specifically, the leading-out positions of the tap lead wires comprise stator windings of the doubly-fed wind generator, slots of different phases of rotor windings, identical coils of different branches of the same phase and coil end parts. In the design stage of the extraction position of the fault tap of the doubly-fed wind generator, the following steps are fully considered: the in-slot taps of different phases, the multiple taps led out from the same coil of different branches of the same phase simulate turn-to-turn short circuits of different turns, and the taps led out from the ends of the coil simulate end turn-to-turn short circuits, which are compared with the in-slot turn-to-turn short circuits.
Specifically, for simulating each short-circuit fault of the doubly-fed wind generator, a lead is led out from a winding of the doubly-fed wind generator when the winding is off-line, and the method specifically comprises the following steps: the method comprises the steps of firstly locally damaging an insulating layer of a normal coil at a preset position, then welding a lead, finally wrapping a welding point with insulating paper, and connecting the welding lead into a junction box at the top of the motor. In the process of processing the generator, the leading-out wire of the tap needs to be specially processed, a welding point is wrapped by insulating paper, and the insulating strength of the position of the leading-out wire is enhanced. And drying and forming the impregnated winding to realize turn-to-turn insulation of the coil winding. After being led out, taps in the generator winding are fixed in the junction box in a centralized mode, and short circuit identification is made.
Specifically, the short-circuit switch console adopts a PLC (programmable logic controller) to control the switching action of the short-circuit switch cabinet, so that short-circuit faults are realized, the short-circuit time is limited to 1s in order to ensure the continuous work of the generator, and the short-circuit control circuit is automatically switched off after 1 s.
Specifically, the plane of the magnetic loop antenna is parallel to the end of the doubly-fed wind driven generator and the radial housing, and the number of the magnetic loop antennas is at least two and the two magnetic loop antennas are arranged at the end of the doubly-fed wind driven generator and in the radial direction of the housing. The magnetic loop antenna is respectively parallel to the end part of the generator and the radial casing, the distance is kept to be 70mm, and the magnetic loop antenna is ensured to be placed on the parallel surface of the air gap hole and the gap of the generator as far as possible. And the placement positions of the magnetic rings are reasonably arranged according to the number of the magnetic ring antennas. The number of the magnetic loop antennas is at least 2, one of the magnetic loop antennas is located at the axial position of the non-driving end of the generator, the position of the central shaft of the end part is optimal, and the magnetic loop antennas can be considered to be placed at the thin-wall gap of the machine groove at the edge of the end part; the radial positions can be provided with different numbers of magnetic loop antennas according to the requirement, and 1-4 magnetic loop antennas can be considered and are uniformly arranged at the radial positions of the generator.
Specifically, a tap is led out from each phase of winding of the doubly-fed wind generator, and a tap leading-out end is arranged in a winding junction box and is connected with the short-circuit control circuit through the junction box.
Specifically, as shown in fig. 1, a schematic diagram of a short-circuit fault experimental platform of a doubly-fed wind turbine is shown. The frequency converter adjusts the frequency and the rotating speed of the dragging motor, the dragging motor drags the doubly-fed wind driven generator coaxially, and the change of the rotating speed of a rotor of the doubly-fed wind driven generator along with the change of the wind speed is simulated, so that the doubly-fed wind driven generator operates at different rotating speeds; the double-fed converter adjusts the output power and the load of the double-fed wind driven generator, and the grid-connected operation of the double-fed wind driven generator is realized. The double-fed wind driven generator internal winding leading-out tap is externally connected with a short circuit control circuit through a junction box, and short circuit conditions of different types and different degrees, such as stator and rotor turn-to-turn short circuit, interphase short circuit, interlayer short circuit, ground short circuit and the like can be simulated. As shown in fig. 2, a stator short-circuit lead is used for illustration, and 1# -8 # taps are led out from an a-phase in-slot winding to realize 2-8 turns of turn-to-turn short circuit of a stator a phase; the 13# -16 # taps are led out from the end part of the A-phase winding to realize turn-to-turn short circuit of 5, 10, 15, 20 and 25 turns of the A-phase of the stator, and different types of short circuit faults can be conveniently selected through identification of lead terminals of the junction box. As shown in table 3:
TABLE 3 correspondence table for short-circuit winding tap lead position and different fault types of doubly-fed generator
Specifically, as shown in fig. 3, a stator and a rotor of the doubly-fed wind turbine are connected in a short-circuit manner. The short-circuit switch cabinet leads out a short-circuit loop from a junction box lead of the doubly-fed wind driven generator through a short-circuit control circuit formed by a breaker QF, an alternating current contactor KM and a short-circuit protection resistor, wherein one short-circuit loop needs 1 breaker QF, 1 alternating current contactor KM and one series short-circuit protection resistor R. The switch cabinet control console adopts a PLC (programmable logic controller), as shown in fig. 4, a PLC control circuit is adopted, the control of the alternating current contactor KM is realized, the auxiliary contact of the alternating current contactor is electrified, the alternating current contactor is closed, the auxiliary contact is electrified after 1s, the alternating current contactor is automatically disconnected, and the PLC can effectively control the closing time of the short-circuit switch, so that the fault is removed in a short time, and the motor is protected to run under the normal condition. Short-circuit protection resistors R with different powers and different resistance values are configured in the short-circuit switch cabinet, the selection of the size of the short-circuit resistor is related to the fault type, a larger resistance value is selected for a more serious fault, and a short-circuit loop is connected to limit short-circuit current; the short-circuit experiment is repeated for many times, and the series short-circuit protection resistor can also play a protection role; when the current of the short circuit loop is overlarge, the circuit breaker QF is automatically switched off to protect the doubly-fed wind driven generator.
Specifically, the leakage magnetic flux monitoring module collects external leakage magnetic signals of the doubly-fed wind generator through magnetic ring antenna arrays arranged at different axial and radial positions of the doubly-fed wind generator, the output end of each magnetic ring antenna is connected with a digital collection card and is connected with a computer C # virtual instrument through an upper computer, and the C # virtual instrument processes and analyzes the signals and displays the signals visually.
Preferably, one magnetic loop antenna is arranged at the axial position of the non-driving end of the generator, one magnetic loop antenna is arranged at the axial position of the driving end, and three magnetic loop antennas are uniformly arranged in the radial direction of the casing. Fig. 5 is a schematic diagram of a test position of the magnetic loop antenna array. The magnetic loop antenna monitors magnetic flux leakage signals outside the generator, and when the magnetic loop antenna is tested, the plane where the magnetic loop antenna is located is kept parallel to the end portion of the generator and the radial shell, the distance is kept to be 70mm, and the magnetic loop antenna is guaranteed to be placed on the parallel surface of the air gap hole and the gap of the generator as far as possible. The base of the loop antenna is made of non-metal materials, extends forwards by 70mm and can be conveniently used for determining the distance of 70mm from the generator testing surface.
Specifically, the hardware of the leakage magnetic flux monitoring module mainly obtains leakage magnetic data, a high-voltage probe captures the action moment of a short-circuit switch to obtain a trigger signal acquired by a leakage magnetic signal, the C # virtual instrument can set pre-trigger, trigger mode, sampling frequency and the like, data is analyzed and processed by adopting a signal processing method after the data is acquired, a time domain and frequency domain signal processing method is usually adopted, meanwhile, the data acquisition card can simultaneously acquire magnetic flux leakage signals at different positions, for example, as shown in FIG. 6(a), FIG. 6(b), FIG. 6(c), FIG. 6(d) and FIG. 6(e), actual measurement signals of magnetic loop antennas at different test positions are obtained when the rotation speed is 1800r/min, the load is 50kW and 8 turns of the stator are short-circuited, fig. 7 is a frequency spectrum diagram of an axial leakage signal when the windings are short-circuited 2, 5 and 8, and the external leakage waveform and the frequency spectrum change can be seen when the short-circuit occurs. Although the characteristic change of the generator winding in the short circuit can be obviously seen from the time domain oscillogram and the frequency domain spectrogram, under the strong noise environment of the operation of the generator, the nonlinear and non-gaussian characteristics of the leakage magnetic detection signal are prominent, and the characteristic frequency components of the environmental noise are random in broadband, so that the characteristic frequency components of the leakage magnetic signal are covered to a certain extent, the relatively weak characteristic frequency is completely submerged in the noise, the operation environment of the doubly-fed wind generator is severe in practice, if the conventional signal analysis methods are adopted to carry out the short circuit fault diagnosis, the spectrograms or the time frequency graphs need to be explained by professional knowledge, and the characteristic information is manually screened to be judged depending on the professional ability of experience.
Specifically, leakage magnetic flux monitoring module still includes digital acquisition card and portable computer PC, digital acquisition card is used for gathering the outside magnetic leakage signal of different magnetic ring antennas, portable computer PC carries out signal analysis and visual display through the outside magnetic leakage signal of C # virtual instrument to gathering.
Specifically, consider the validity that strong noise environment magnetic leakage detected, adopted a processing method suitable for magnetic leakage signal analysis, carry out bispectrum analysis to the magnetic leakage signal of gathering, can extract magnetic leakage signal fault characteristic under the strong noise environment effectively through 1.5 dimension envelope spectrums, portable computer PC be used for carrying out signal analysis and visual demonstration to the outside magnetic leakage signal of gathering through C # virtual instrument, include following step:
firstly, setting the rotating speed of a dragging motor, starting a frequency converter, dragging the motor to drive a generator to operate to a specified rotating speed, controlling a double-fed converter to carry out grid-connected operation on a double-fed wind driven generator, adjusting load power, pressing a short-circuit control console short-circuit switch after stable operation, closing the short-circuit switch, and triggering a magnetic flux leakage monitoring module to acquire a magnetic flux leakage signal;
step 1: acquiring external leakage flux signals monitored by magnetic ring antennas at different positions of the wind driven generator through a digital acquisition card;
step 2: performing time domain analysis after wavelet denoising on the acquired leakage magnetic flux signal to judge the fluctuation condition of the leakage magnetic flux signal, and further extracting leakage magnetic flux signal data in a stationary time period according to fluctuation positioning information of the leakage magnetic flux signal;
and step 3: carrying out envelope analysis on the leakage flux signal in the stable time period to extract an envelope signal, carrying out double-spectrum analysis after carrying out Hilbert transform on the envelope signal, and obtaining a double-spectrum estimation characteristic diagram of the leakage flux signal;
and 4, step 4: and carrying out 1.5-dimensional slicing processing on the bispectrum estimation characteristic diagram of the magnetic leakage signal to obtain a 1.5-dimensional envelope spectrogram, carrying out visual display on the 1.5-dimensional envelope spectrogram, further obtaining the characteristic coupling frequency of the magnetic leakage signal, and judging whether the winding short-circuit fault exists or not by comparing and analyzing the characteristic coupling frequency with the spectrogram of the magnetic leakage flux signal in normal operation of the wind driven generator.
Example 1
The embodiment discloses a 100kW double-fed wind driven generator stator, rotor winding short-circuit fault simulation experiment platform, including 100kW three-phase wire winding rotor double-fed induction generator, inverter motor, double-fed converter, short-circuit switch cabinet and control cabinet and outside magnetic leakage flux monitoring module.
As the power of the motor adopted by the current domestic and overseas related researches is smaller and is far from the actual fan, the experimental system adopts a YSF315S-4M double-fed generator with the rated power of 100kW, and the main technical parameters are shown in the table 1.
Table 1 main technical parameters of doubly-fed generator for experimental platform
In order to meet the power requirement of the doubly-fed generator, YCP315M-4 is selected as the variable frequency motor, and the main technical parameters are shown in Table 2.
Table 2 main technical parameters of variable frequency motor for experimental platform
In order to collect leakage flux signals of the generator under normal and different types of short-circuit faults, the IPC model of the short-circuit switch console is IPC-610MB CPU, and the CPU module control circuit of the PLC is S7-200 CPU 226. The magnetic loop antenna adopts an HTANT8001R loop antenna, meets the RE101 test item requirement specified by the national military standard GJB152A-97, has the frequency band range of 30Hz-100kHz, has 36 turns of internal coil, has the diameter of 13.3cm, and has stable and reliable performance at 0 ℃ to 50 ℃. The digital acquisition card adopts the simple instrument technology DDA-9540, and can realize 8-channel synchronous sampling with 24 bits of resolution, 500 Hz-102.4 kHZ of sampling rate and +/-10V of signal input range. The high-pressure probe adopts Tanke P6015A, and the transformation ratio is 1000: 1.
Sampling the leakage magnetic signal of the doubly-fed wind generator, wherein the sampling rate is 102400Hz, the sampling point number is 204800, the pre-sampling point number is 40960 through a C # virtual instrument, the trigger threshold value is 0.25V, and the short-circuit time is controlled by a short-circuit switch console to last for 1 s. Taking 1800r/min as an example, under the grid-connected working condition of 50kW load, the analysis of the end leakage signal when 8 turns of the stator and the rotor are short-circuited is performed, and the double-spectrum analysis is performed on the end leakage signal of the non-driving end when the different turns of the rotor are short-circuited, and as shown in fig. 8(a) and 8(b), the double-spectrum analysis of the end leakage signal when the rotor winding is short-circuited is performed, wherein the double-spectrum estimation characteristic diagram of the leakage signal when the generator normally operates and the 8 turns of the winding are short-circuited is included. As shown in fig. 9(a), 9(b), 9(c) and 9(d), the envelope spectrum of the leakage magnetic signal at the non-driving end when the number of turns is short-circuited is 1.5 dimensions, wherein the envelope spectrum of the leakage magnetic signal includes 1.5 dimensions of the leakage magnetic signal when the generator is in normal operation and when the number of turns is 2, 5 and 8 is short-circuited, it can be seen that high-frequency noise and gaussian noise are suppressed, the characteristic components of the low-order energy spectrum of the external leakage magnetic signal are more prominent, and as the degree of short-circuit fault increases, 1/2 times and 1/3 times of 1 frequency doubling, 3 frequency doubling and fractional number doubling are significantly increased, the spectrum contains characteristic components participating in coupling and coupling generation, and the amplitude also obviously increases, which indicates that nonlinear interaction between different frequency components is generated in the leakage magnetic signal, and 2 phase coupling phenomena exist. Experimental analysis shows that the external leakage flux of the generator is sensitive to noise, the adopted method can effectively extract the influence of nonlinear interaction between the fault characteristic frequencies of the short-circuit fault leakage flux signals on the respective leakage flux characteristic frequencies, particularly when the leakage flux signals are weak, the corresponding fault information is easier to identify, meanwhile, the leakage flux detection analysis mainly in a low-frequency range is more significant, and the method is beneficial to practical engineering application.
Claims (6)
1. The wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection is characterized by being used for simulating the actual operation condition of a double-fed wind driven generator and different short-circuit fault types of the double-fed wind driven generator and comprising the double-fed wind driven generator, a dragging motor, a frequency converter, a double-fed converter, a short-circuit switch cabinet, a short-circuit switch console and a magnetic flux leakage monitoring module, wherein the short-circuit switch console is respectively connected with the short-circuit switch cabinet and the frequency converter, the short-circuit switch cabinet is connected with the double-fed wind driven generator, the dragging motor regulates the double-fed wind driven generator through the frequency converter, and the double-fed wind driven generator is also respectively connected with the double-fed converter and the magnetic flux leakage monitoring module;
the dragging motor is used for driving the double-fed wind driven generator; the frequency converter is used for adjusting the frequency and the rotating speed of the dragging motor; the double-fed converter is used for adjusting the output power and the load of the double-fed wind driven generator; the double-fed wind driven generator is characterized in that a plurality of winding taps are led out from each phase of stator and rotor winding coils of the double-fed wind driven generator, winding tap leads are connected to a junction box wiring terminal block row of the double-fed wind driven generator, the number of the winding leads, the junction box wiring terminal block row and the type of short-circuit faults are in one-to-one correspondence, the winding taps are connected with an external short-circuit switch cabinet through the junction box wiring terminal block row, and the short-circuit faults with different turns are realized through the mutual connection of the winding taps; the short-circuit switch cabinet is used for simulating the short-circuit fault of the double-fed wind driven generator and is connected with a tap lead of a winding of the double-fed wind driven generator through a short-circuit control circuit to simulate and control external short circuit; the short-circuit switch console is used for controlling a short-circuit control circuit in the short-circuit switch cabinet; the leakage magnetic flux monitoring module is used for acquiring external leakage magnetic signals of the doubly-fed wind generator, and performing signal analysis and visual display on the external leakage magnetic signals;
the short-circuit switch cabinet comprises a short-circuit control circuit and a short-circuit protection resistor, wherein the short-circuit control circuit is composed of an alternating current contactor and a breaker, the short-circuit control circuit is connected with the alternating current contactor and the breaker in series, and the alternating current contactor is in a normally open state; the short-circuit protection resistor is connected into the short-circuit control circuit and used for limiting current and protecting the doubly-fed wind generator to repeatedly perform a short-circuit experiment for many times; the short circuit control circuit is connected with the junction box of the double-fed wind driven generator, and the short circuit switch console controls the auxiliary contact of the alternating current contactor to be attracted, so that turn-to-turn short circuit fault is caused; the magnetic leakage flux monitoring module comprises a magnetic loop antenna array, a digital acquisition card and a portable computer, wherein the magnetic loop antenna array comprises a plurality of magnetic loop antennas, and the output end of each magnetic loop antenna is connected with the digital acquisition card. The magnetic ring antenna is arranged at different axial and radial positions of the doubly-fed wind driven generator, the digital acquisition card is used for acquiring magnetic leakage signals monitored by the magnetic ring antenna at different positions, and the portable computer performs data analysis and visual display on the acquired magnetic leakage signals through a C # virtual instrument.
2. The wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection as claimed in claim 1, wherein the short-circuit control circuit is sequentially connected with a terminal block row of a junction box of the doubly-fed wind driven generator, a circuit breaker, an alternating current contactor and a short-circuit protection resistor, and the terminal block row of the junction box of the doubly-fed wind driven generator is arranged on tap leads of different numbers of a stator winding and a rotor winding of the doubly-fed wind driven generator; the leading-out positions of the tap leads comprise stator windings of the doubly-fed wind generator, different-phase slots of rotor windings, same coils of different branches of the same phase and coil end parts.
3. The wind driven generator short-circuit fault simulation platform based on external magnetic flux leakage detection as claimed in claim 1, wherein the short-circuit switch console adopts a PLC programmable controller to control the switching action of the short-circuit switch cabinet, controls the auxiliary contact of the AC contactor to be electrified and closed to cause inter-turn short-circuit fault, and after the auxiliary contact of the AC contactor is closed for 1s, the AC contactor is disconnected in power loss mode, and the doubly-fed wind driven generator recovers normal operation.
4. The platform for simulating short-circuit fault of wind driven generator based on external magnetic leakage detection as claimed in claim 1, wherein the signal data analysis and visual display of the collected magnetic leakage signal by the portable computer through a C # virtual instrument comprises the following steps:
step 1: acquiring magnetic flux leakage signals monitored by magnetic ring antennas at different positions of the doubly-fed wind generator through a digital acquisition card;
step 2: performing time domain analysis after wavelet denoising on the acquired leakage magnetic flux signal to judge the fluctuation condition of the leakage magnetic flux signal, and further extracting leakage magnetic flux signal data in a stationary time period according to fluctuation positioning information of the leakage magnetic flux signal;
and step 3: carrying out envelope analysis on the leakage flux signal in the stable time period to extract an envelope signal, carrying out double-spectrum analysis after carrying out Hilbert transform on the envelope signal, and obtaining a double-spectrum estimation characteristic diagram of the leakage flux signal;
and 4, step 4: and carrying out 1.5-dimensional slicing processing on the bispectrum estimation characteristic diagram of the magnetic leakage signal to obtain a 1.5-dimensional envelope spectrogram, carrying out visual display on the envelope spectrogram, further obtaining the characteristic frequency of the magnetic leakage signal, and judging whether the winding short-circuit fault exists or not through comparison and analysis with the spectrogram of the magnetic leakage flux signal of the normal operation of the doubly-fed wind driven generator.
5. The wind power generator short-circuit fault simulation platform based on external magnetic flux leakage detection as claimed in claim 1, wherein the planes of the magnetic loop antennas are respectively parallel to the end portion of the doubly-fed wind power generator and the radial housing, and the number of the magnetic loop antennas is at least two and is respectively arranged in the axial direction of the end portion of the doubly-fed wind power generator and in the radial direction of the housing.
6. The wind turbine generator short-circuit fault simulation platform based on external magnetic flux leakage detection as claimed in claim 4, wherein the magnetic loop antenna is arranged at one axial position of the non-driving end of the doubly-fed wind turbine generator, at one axial position of the non-driving end, and at three axial positions uniformly arranged in the radial direction of the housing.
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